I have just started looking at The Cognitive Dvelopmental Psychology of James Mark Baldwin: Current Theory and Research in Genetic Epistemology, edited by John M. Broughton and D. John Freeman Moir. I was able to get an inexpensive used (ex-library) copy through Amazon.
I picked it up on Steve McIntosh's recommendation. Steve's book on integralism as an emerging cultural stage will be coming out in the near future.
I am finding the book on Baldwin easy to read and informative so far, and am appreciating the authors' comprehensive and contextual approaches.
I would love to know of anything out there that is even more introductory, though.
Good Luck!
Mary Anne Cutaia